Used on 1940 supercharged, carburetor model 473-S and non-supercharged engines, carburetor model 472-S. The body casting number for both carburetors is 309. The thermostatic coil setting is one notch rich.
The unloader setting uses gauge number T109-83, choke valve clearance ½.
The float inlet valve number is 25-42S, the intake hole size #38.
The throttle valve setting for the idle port opening is .133-.137, vacuum port height .029-.034
The anti-percolator setting use gauge T109-29, throttle opening .030
The float level setting is 3/8 and to check the level, invert cover, measure from top edge of machined projection on cover at free end of float to top of soldered seam. Adjust by bending lip of float lever.
Turning the idle setscrew ½ to 1 ½ turns sets the idle setting. Idle speed 7-8 mph.
The accelerator pump stroke is 19/64 using the medium pump stroke.